The present invention relates generally to stormwater management, and more particularly, to a stormwater pollutant separation system and its method of use, and even more particularly to a component of that system, a stormwater pollutant separator.
This invention is directed to the providing of a pollutant separation system for use in stormwater management. Historically, stormwater management has been primarily concerned with the control of erosion and sedimentation during and as a result of construction, and with the control of discharge from a site following construction so that the amount of discharge was either the same or less than under pre-developed conditions. The former concern addressed water quality during construction, while the latter concern prevented downstream flooding from the change in land use. However, neither concern considered how post-development water quality was impacted.
However, beginning in 1972, the importance of water quality and the impact of construction on natural streams and watercourses was recognized and federally regulated. For example, the Clean Water Act allowed for federal regulation of construction activities to insure the impact on water quality was minimized. Inlet protection, channel liners, vegetation, seeding and sodding, silt fences and sediment ponds all became associated with construction activity. Any construction activity which disturbed five or more acres required permitting to insure proper erosion control methods were utilized during construction.
Subsequently, most state and local communities have enacted legislation requiring all construction projects to incorporate some level of erosion and sediment control during construction. Today therefore it is common practice to incorporate a variety of erosion and sediment control devices and techniques in connection with construction projects.
As beneficial as legislation directed to erosion control of stormwater was, the nation""s water quality continued to decline. Therefore, in 1999 the Phase II Clean Water Act was enacted. Each municipality covered by the Act is required to demonstrate Best Management Practices (BMP) in a number of areas, one of which concerns post-construction runoff controls. One of the areas requires that regulated municipalities have a program that reduces pollutants for new and redevelopment projects. In connection with new construction, the possible BMPs include watertight pipes, retention/detention systems, inlet control devices, and water quality units for stormwater.
One particular area of concern is runoff from new construction, particularly parking lots. In fact, some studies have found that the largest source of pollutants at the current time being discharged into receiving waters is from stormwater runoff. Thus, there is considerable interest in trying to decrease the amount of sediment, oil, grease, and other contaminants being discharged into streams, rivers, and other bodies of water. Stormwater pollutant separation systems have been developed for installation below grade as part of the stormwater drainage system.
These systems have been designed to accommodate and treat the stormwater associated with two very important and distinct time periods. The first time period is known in the industry as xe2x80x9cfirst flushxe2x80x9d. This term is used to describe the design discharge to be treated. Although local definitions vary, typical first flush designs are the first xc2xdxe2x80x3 to 1xe2x80x3 rainfall for a 6 to 12 month return period. This stormwater runoff occurs near the beginning of a storm when the amount of precipitation becomes sufficient to cause the dirt and oil on the surface of a parking lot, by way of example, to flow into the drainage grates and enter the stormwater drainage system.
The other time period occurs when a storm is strong enough to cause a large volume of water to enter the stormwater drainage system. This large volume of water requires that the rate of ingress through the system attempt to avoid back-up and actual preclusion of some water from being able to enter the storm grate, thereby causing surface flooding.
As important as it is to address the problem of oil in runoff, there are two additional areas of concern. The first area concerns heavy metal pollutants. Lead from automotive brake pads, cadmium and nickel from combustion due to normal engine wear, and zinc from the galvanizing of automotive parts"" coatings all make their way into stormwater runoff. The second area concerns phosphates and nitrates commonly introduced into stormwater runoff as a consequence of their use in fertilizer which may have been applied to grass, flowers, shrubs, and trees.
There have been several attempts at providing stormwater pollutant separation systems. For example, Pank, U.S. Pat. No. 5,746,911, discloses an apparatus for separating a light from a heavy fluid, such as occurs as between oil and water from parking lot run-off. The system utilizes two large tanks connected to each other by a pair of conduits. Under most conditions, water flow enters the inlet tank, flows into the separation tank, and then finally flows from the separation tank to the outlet conduit. However, when the system is subjected to a heavy rain, the fluid level in the inlet tank rises to a level at which there is a direct overflow into the outlet conduit.
Adams, U.S. Pat. No. 5,759,415, discloses a method and apparatus for separating floating and non-floating particulate from rainwater drainage. A particulate container chamber is utilized, and an embodiment for separating oil is shown in FIG. 12, with a separate oil/water separator being coupled to the tank of the invention. In the embodiment of that invention as marketed by Vortechnics, Inc. of Portland, Me., the system is fabricated near the jobsite from pre-cast concrete and marine grade aluminum. Unlike Pank, even in heavy rain conditions the path of flow through the Adams apparatus remains virtually the same. Moreover, in the apparatus of Adams as in Pank, the input flow equals the output flow, such that there is no way to control the velocity of the liquid passing through either system.
However, the potential exists with either system to partially flush captured contaminants, especially under heavy rain conditions. Additionally, the fact that all input flow must pass into the inlet tank or area before entering the outlet conduit creates the possibility of backup unless the system is made relatively large, which adversely impacts on price and size considerations.
It is thus apparent that the need exists for a stormwater pollutant separation system which can control the velocity of the fluid passing through the system while at the same time prevent the flushing of captured pollutants, including heavy metals, phosphates, and nitrates.
In accordance with this invention a stormwater pollutant separator system is provided with the system having a stormwater pollutant separator, a by-pass system, an intake conduit and an outflow conduit. The stormwater pollutant separator has a chamber having a first end and a second end, a top and a bottom. A weir plate is attached to and extends upwardly from the chamber bottom. A siphon plate is attached to and extends downwardly from the chamber top.
A plurality of inspection/maintenance risers are attached to and extend upwardly from the stormwater pollutant separator. The first end of the chamber of the stormwater pollutant separator has an intake aperture formed therein. Similarly, the second end has an outflow aperture formed therein.
The by-pass system has a first end and a second end, with the intake conduit connecting the first end of the stormwater pollutant separator and the first end of the by-pass system, and with the outflow conduit connecting the second end of the stormwater pollutant separator and the second end of the by-pass system.
The chamber of the stormwater pollutant separator system has a first section, a second section, and a third section. The first section is located between the first end of the chamber and the weir plate. The second section is located between the weir plate and the siphon plate. The third section is located between the siphon plate and the second end of the chamber.
The first section preferably has an inspection/maintenance riser connected thereto which extends upwardly therefrom. The second section preferably has an inspection/maintenance riser connected thereto which extends upwardly therefrom. The third section in at least one embodiment has an inspection/maintenance riser connected thereto which extends upwardly therefrom. In that embodiment the third section has the potential for having filter material placed intermediate the siphon plate and the second end plate, with the filter material being adjacent the outflow aperture.
In that embodiment the third section preferably has a standpipe having a top and a bottom, with the standpipe top attached to and extending downwardly from the chamber top. The standpipe has a plurality of apertures formed therein below the outlet aperture, with the filter material being located within the interior of the standpipe. In at least one embodiment, the standpipe has an end plate attached at the standpipe bottom, and at least in one embodiment the standpipe end plate has apertures formed therein.
The chamber preferably includes a stiffener plate attached to and extending inwardly from the first end of the chamber, and a dispersion baffle having a top and a bottom, with the baffle top attached to the chamber top and the baffle bottom attached to the stiffener plate.
The intake conduit features a connector having an upwardly extending portion and a downwardly extending portion, with the upwardly extending portion preferably having an inspection/maintenance riser, and with the downwardly extending portion being connected to at least one piece of conduit also connected to the stormwater pollutant separator. The by-pass system includes a by-pass conduit and a by-pass connector, with the by-pass connector attached to the by-pass conduit and to the outflow conduit.
There is also disclosed a stormwater pollutant separator having a chamber and a plurality of inspection/maintenance risers. The chamber has a top and a bottom, and a first end and a second end. The first end of the chamber of the stormwater pollutant separator has an intake aperture formed therein, and the second end has an outflow aperture formed therein. A weir plate is attached to and extends upwardly from the chamber bottom, while a siphon plate is attached to and extends downwardly from the chamber top. The inspection/maintenance risers are attached to and extend upwardly from the stormwater pollutant separator.
The stormwater pollutant separator chamber features a first section, a second section, and a third section, with the first section being located between the first end and the weir plate, the second section being located between the weir plate and the siphon plate, and the third section being located between the siphon plate and the second end. The first section has one of the inspection/maintenance risers connected thereto and extending upwardly therefrom. Similarly, the second section has one of the inspection/maintenance risers connected thereto and extending upwardly therefrom. Preferably, the third section has one of the inspection/maintenance risers connected thereto and extending upwardly therefrom. Preferably, the third section has filter material placed intermediate the siphon plate and the second end plate, with the filter material being adjacent the outflow aperture.
Preferably, the third section has a standpipe, with the standpipe having a top and a bottom, and with the standpipe top attached to and extending downwardly from the chamber top. The standpipe has a plurality of apertures formed therein. The filter material is placed within the interior of the standpipe. The optional standpipe has an end plate attached at the standpipe bottom, and preferably the standpipe end plate has apertures formed therein.
The stormwater pollutant separator chamber preferably includes a stiffener plate attached to and extending inwardly from the first end, as well as a dispersion baffle having a top and a bottom. The baffle top is attached to the chamber top and the baffle bottom is attached to the stiffener plate.
There is also disclosed a method for separating floating and non-floating material from stormwater drainage, with the method including the steps of inducing the stormwater drainage initially into a stormwater pollutant separator for flow therethrough, containing the majority of all non-floating material by the use of a weir plate within the stormwater pollution separator, containing the majority of all floating material by the use of a siphon plate within the stormwater pollution separator, discharging the stormwater drainage from the stormwater pollutant separator, providing a by-pass system for introduction of stormwater drainage thereinto for flow therethrough when the level of stormwater drainage awaiting introduction into the stormwater pollutant separator results in overflow into the by-pass system, and discharging any stormwater drainage from the by-pass system into the stormwater drainage discharged from the stormwater pollutant separator.
The method includes the additional step of removing some of the suspended solids in the stormwater drainage, in particular, heavy metals, phosphates, and nitrates, by introducing a filtering material within the stormwater pollutant separator prior to the discharge of the stormwater drainage from the stormwater pollutant separator. The stormwater pollutant separator has an outlet aperture sized to regulate the rate of flow of the stormwater drainage through the stormwater pollutant separator. The stormwater pollutant separator also has an intake aperture through which the stormwater drainage is introduced into the stormwater pollution separator, with the stormwater pollution separator preferably having a dispersion baffle located adjacent the intake aperture.
The primary objective of this invention is to provide a stormwater pollutant separation system which can control the velocity of the fluid passing through the system while at the same time prevent the flushing of captured pollutants, including sediment, hydrocarbons, and suspended solids such as heavy metals, phosphates, and nitrates. An important aspect of this objective is the providing of a unique stormwater pollutant separator which can separate sediment, floating material and suspended solids including heavy metals, phosphates, and nitrates.
Another objective is to provide a stormwater pollutant separation system that can control both flow and peak flow. An important aspect of this is the providing of a by-pass system that works in conjunction with the stormwater pollutant separator.
Another objective is to provide a stormwater pollutant separation system that is of relatively economical construction and is relatively easy to fabricate.
Still another objective is to provide a stormwater pollutant separation system that can be installed on site relatively easily.
Yet still another objective is to provide a method for use of the system of this invention.
Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings, and the appended claims.